The use of communication systems through which to communicate data is an endemic part of modem society. Telephonic communication systems are, perhaps, best exemplary of communication systems that have been widely employed and are regularly utilized by large numbers of users.
In a telephonic communication system, telephonic communication of voice, as well as non-voice, data is generally provided. Telephonic communication networks have been installed throughout significant portions of the world, and users communicate telephonically therethrough by way of telephonic, or other communication, stations connected to the telephonic networks.
Conventionally, telephonic networks provide for circuit-switched communications between telephonic stations that are to be connected to effectuate a communication session therebetween. When a circuit-switched connection is formed, a dedicated channel is provided to permit the telephonic communications between the telephonic stations, a calling party and at least one called party, is provided. For so long as the connection is maintained, telephonic communications between the telephonic stations is permitted. As data forming the telephonic communication might only be intermittently communicated between the telephonic stations during the communication session effectuated by way of the circuit-switched connection, the communication capacity of communication channels defined upon the circuit-switched connection might well not be fully utilized. Use of circuit-switched connections, formed in a telephonic network, as a result, inefficiently utilizes the communication capacity of a telephonic network.
Communication schemes which provide for shared-channel communications, in contrast, more efficiently utilize the communication capacity of a communication system, such as a telephonic communication system. Packet-based communication systems, for instance, utilize shared channels upon which to communicate packet-formatted data. When a shared channel is utilized, more than one communication session is effectuable upon a single shared channel. Because packet-formatted data can be communicated during discrete intervals, the same channel can be utilized to communicate packet-formatted data, during separate time periods to effectuate communication services pursuant to separate communication sessions. More efficient utilization of the communication capacity of a communication system is thereby possible, in contrast, to conventional circuit-switched communication schemes.
Various packet formatting protocols are used when forming, and sending, data packets formed of digital data bits. One protocol scheme, the Internet protocol (IP), or IP protocol, is regularly utilized in many different communication systems and communication applications. Communication devices and apparatus constructed to send, receive, transport, and operate upon IP-formatted data can be configured together in a communication system to provide for the communication of IP-formatted data.
Next-generation telephonic communication systems now being developed include telephonic networks that are predicated upon packet-based communications. In such next-generation systems, voice, non-voice, and multimedia communication services shall be effectuable through the use of packet-based communications, using IP-formatted data.
Such a new-generation telephonic network generally includes a packet data network, or fabric, through which packet-switched channels are formed. Devices referred to as gateways are coupled to the packet data network. Devices referred to as gateways form gateways to the packet data network. Gateways are operable, amongst other things, to form gateways to the packet data network from local networks. When communications in a local network are effectuated using a different type of communication protocol than the protocol used in the packet data network, the gateway connecting the local network to the packet data network performs protocol translation, as well as, perhaps, also voice encoding operations.
For instance, a local network might form a legacy, TDM (time division multiplexed) network. The call handling procedures of the local network would therefore be different than that of a packet-based network.
Operational control of the telephonic communication system is effectuated by a softswitch that functionally forms a part of, or is connected to, the packet data network. The softswitch operates to control connection services of the gateways, operates to control call routing based upon signaling information and database information related to the calling party and called party.
Public safety answering points are amongst the communication devices that can be connected to a packet data network by way of a gateway. An emergency dispatch center is, for instance, the location to which an emergency call, such as a “911 call” in the United States is routed. Such a call is originated at a calling station located at a local network, through a gateway connecting the local network to the packet data network, through the packet data network, to the gateway to which the public service access point is located.
While the new-generation, telephonic networks include various redundancies, such as redundant softswitches, in the event of total failure of a communication link between the gateway to which the local network is coupled and a softswitch associated with the packet data network, the call originated at the telephonic station of the local network cannot be routed to the public safety answering point. Other calls analogously originated at the telephonic station of the local network also cannot be completed. Included amongst the additional calls that cannot be completed are calls to a called party, i.e., the terminating station, at the local network. That is to say, even if a local call is to be originated and terminated entirely within a local network, the new-generation telephonic communication system would not be able to complete such a call.
Calls within the local network could still be completed in spite of the total failure of the communication link, but for the external control provided only by the softswitch in the next-generation system. That is to say, the call handling functionality provided by the softswitch, but unavailable due to the failure of the communication link, prevents continued operation of calls within the local network.
If a manner could be provided by which to provide local call control in the event of failure of a communication link, at least limited communications within the local network could still be effectuable. And, if the local calls could still be effectuable, a call originated at the local network for termination at the public safety answering point could be routed, instead, to a local-network, telephonic station thereby to complete the call another party.
It is in light of this background information related to packet-based, telephonic communication systems that the significant improvements of the present invention have evolved.